Security group G4S appeared to bounce back from its Olympic contract shambles with a rise in revenues but the company admitted there was still work to be done to rebuild its reputation.

The company said revenues rose 4.1pc in the first nine months of the year, or 6.9pc including the London 2012 contract, Operating margins were lower compared with the same period last year.

The update from G4S was welcomed by the City and shares rose 3.5pc to 270p. However, contracts to run nine British prisons to be awarded this week will be a key test of whether the Government is willing to forgive its Olympics mishap and farm out new contracts to the company.

Nick Buckles, the company’s chief executive who survived the Olympics debacle said that while it would be “disappointing” if G4S did not win any of the contracts, there would be other opportunities. He added: “The business has rebuilt itself pretty well but we have still got some work to do.

“Clearly [the Olympic contract] was a disappointing experience but we are still performing pretty well and the pipeline is looking good. Outside the UK - and without wanting to sound complacent - I don’t think it has made a huge difference to our reputation.”

G4S has already booked a £50m loss against the Olympic contract, based on the company’s estimate.

The organisers of London 2012 suspended payments to G4S on July 13 when it became clear the company would not be able to provide all the security staff it had agreed to.

Mr Buckles said it was still in negotiation with Locog over how much it would ultimately be paid of an agreed £240m contract. He said he hoped the negotiations would be settled by the end of the year.

G4S is in the process of appointing a group chief operating officer, following an internal review of what went wrong with the Olympics contract, commissioned by the board and led by PricewaterhouseCoopers, which identified failings in operational procedures.

Mr Buckles said the company had drawn up a long list of candidates, and hoped to make an appointment early in the new year. He said the new COO would be responsible for improving margins as well as operations.

The company said that while the UK business had improved, the US government market and Europe were still tough.